KR20180122623A - Hollow fiber membrane - Google Patents

Abstract

The hollow fiber membrane of the present invention includes a dense layer having only a hole having a hole area of 0.28 탆 ² or less in a state of being observed in a cross section perpendicular to the longitudinal direction of the hollow fiber membrane, The outer diameter of which is not more than 350 mu m, the inner diameter is not less than 150 mu m, the film thickness is not less than 30 mu m and not more than 90 mu m, the surface of the hollow fiber membrane on which the dense layer is arranged has a plurality of holes, (DT / WT) of the thickness (DT) of the dense layer and the film thickness (WT) of the hollow fiber membrane is not less than 0.24, and the average pore diameter observed on the hollow fiber membrane surface of the hole is not less than 0.3 mu m and not more than 0.9 mu m.

Description

Hollow fiber membrane

The present invention relates to a hollow fiber membrane.

BACKGROUND OF THE INVENTION [0002] Hollow fiber membranes have heretofore been widely used in fields ranging from reverse osmosis to microfiltration. It is widely used for medical treatment such as a blood purifier for a kidney failure patient or water treatment for a water purifier.

As the material of the hollow fiber membrane, hydrophobic polymers such as polyethylene and polysulfone are known, and it is known that the hollow fiber membrane using the material is subjected to hydrophilization treatment. The hydrophilization treatment includes a method of coating a hydrophilic polymer after forming a hollow fiber membrane, a method of imparting hydrophilicity by discharging an injection solution containing a hydrophilic polymer together with a spinning solution of a hollow fiber membrane from a spinneret of a double ring. This hydrophilization treatment improves the permeability of the hollow fiber membrane.

In addition, characteristics required for cartridges for water purifiers are those having high resistance to water pressure, high water permeability, high material removal characteristics, and long cartridge life. For this purpose, hollow fiber membranes for water purifiers have been developed which have high strength to withstand water pressure and high water permeability and sharp material fractionation performance.

For example, Patent Document 1 discloses a method of spinning a hollow fiber membrane at a high radiation draft rate of 100 or 185 in a melt spinning method in order to improve resistance to high water pressure.

Patent Document 2 discloses a method of controlling the pore structure of a membrane by controlling the radiation draft rate and increasing the water permeability in a hollow fiber membrane having an asymmetric structure in which a dense layer is formed.

It is also known that it is effective to increase the area of the hollow fiber membrane in order to extend the service life of the water purifier cartridge.

Japanese Patent Laid-Open No. 04-018112 International Publication No. 2010/029908

However, the hollow fiber membrane obtained by the production method disclosed in Patent Document 1 is excellent in resistance to high water pressure, but since the cross-sectional structure of the hollow fiber membrane is uniform, that is, the fine holes present in the cross section of the hollow fiber membrane are dense, There is a problem of falling. Here, as means for increasing the water permeability of the hollow fiber membrane, it is considered to increase the hole area of the fine holes, but in this case, there is a problem that the hollow fiber membrane is poor in the fractionation performance.

Further, the hollow fiber membrane disclosed in Patent Document 2 has a dense layer and a non-dense layer, and the pore structure is controlled, so that the water permeability is excellent. However, there is a problem that resistance to high water pressure is poor.

Further, there is a problem that, when the membrane area of the hollow fiber membrane provided in the water purifier cartridge is increased in order to prolong the product life of the water purifier cartridge (hereinafter sometimes referred to as the cartridge) having the hollow fiber membrane, the size of the cartridge is increased. Therefore, in order to suppress the enlargement of the cartridge while increasing the membrane area of the hollow fiber membrane, it is considered to cure the hollow fiber membrane. However, in this case, the hollow fiber membrane tends to be poor in resistance to high water pressure and poor in water permeability . Further, when the hollow fiber membrane having a dense layer is cured, the resistance to high water pressure of the hollow fiber membrane is further deteriorated.

SUMMARY OF THE INVENTION Accordingly, it is an object of the present invention to provide a hollow fiber membrane excellent in resistance to high water pressure and excellent in water permeability, and to realize a long life of a water purifier cartridge in which a hollow fiber membrane is mounted.

In order to solve the above problems, the present invention features the following (1) to (5).

(1) A hollow fiber membrane having a dense layer having only a hole having a hole area of 0.28 탆 ² or less in a state observed in a cross section perpendicular to the longitudinal direction of the hollow fiber membrane, wherein the dense layer is formed on the outer surface side of the hollow fiber membrane The outer diameter of the hollow fiber membrane is 350 占 퐉 or less, the inner diameter of the hollow fiber membrane is 150 占 퐉 or more, the membrane thickness of the hollow fiber membrane is 30 占 퐉 or more and 90 占 퐉 or less, Wherein the surface of the hollow fiber membrane has a plurality of holes and an average pore diameter observed from the surface of the hollow fiber membranes of the plurality of holes is not less than 0.3 mu m and not more than 0.9 mu m, Wherein a ratio (DT / WT) of the film thickness (WT) is 0.24 or more.

(2) The hollow fiber membrane according to (1), wherein the dense layer is disposed on the outer surface side of the hollow fiber membrane.

(3) The hollow fiber membrane according to (1) or (2) above, wherein the open area ratio of the surface of the hollow fiber membrane on which the dense layer is disposed is 15% or more and 45% or less.

(4) The hollow fiber membrane according to any one of (1) to (3), wherein the hollow fiber membrane comprises a polysulfone-based polymer and polyvinylpyrrolidone.

(5) A cartridge for a water purifier equipped with the hollow fiber membrane according to any one of (1) to (4).

(Effects of the Invention)

According to the present invention, it is possible to provide a hollow fiber membrane excellent in resistance to high water pressure and excellent in water permeability, and to realize a long life of a water purifier cartridge in which a hollow fiber membrane is mounted.

Hereinafter, a preferred embodiment of the present invention will be described in detail.

Also, in this specification, all percentages or parts expressed by mass are the same as percentages or parts expressed by weight.

In the prior art, when the hollow fiber membrane having the dense layer is cured, the resistance to high water pressure of the hollow fiber membrane is poor (the strength of the hollow fiber membrane is lowered), and sufficient water permeability is not obtained. Therefore, the present inventors have found that the outer diameter, the inner diameter, the film thickness, and the structure of the dense layer of the hollow fiber significantly affect the strength improvement and permeability of the hollow fiber membrane, according, a hollow fiber membrane having a dense layer having only a hole area less than or equal to ² 0.28㎛ hole, there is a dense layer is disposed on the front surface or the inner surface of the outer side of the hollow fiber membrane, it is less than the outer diameter of the hollow fiber membrane 350㎛, Wherein the hollow fiber membrane has an inner diameter of 150 mu m or more and a hollow fiber membrane thickness of 30 mu m or more and 90 mu m or less and the surface of the hollow fiber membrane on which the dense layer is arranged has a plurality of holes, The hollow fiber membrane of the present invention having an average pore diameter of not less than 0.3 탆 and not more than 0.9 탆 observed and having a ratio of the ratio of the thickness (DT) of the dense layer to the film thickness (WT) of the hollow fiber membrane (DT / WT)

As described above, since the hollow fiber membrane of the present invention has a small outer diameter of 350 mu m or less, it can be mounted in a number of compact hollow fiber membrane modules (hereinafter may be referred to as modules) and cartridges for water purifiers, The life of the product can be made excellent.

From the viewpoint of better water permeability and product life of the cartridge, it is preferable that the hollow fiber membrane has a small outer diameter, a large inner diameter, and a thin film thickness. From the viewpoint that the strength of the hollow fiber membrane is excellent, it is preferable that the hollow fiber membrane has a large outer diameter, a small inner diameter, and a large membrane thickness. It is important to control the structure of the dense layer in order to make these opposite conditions compatible. The structure of the dense layer greatly affects the strength maintenance and permeability of the membrane. In view of the above, it is important that the hollow fiber membrane has an outer diameter of 350 mu m or less, and the lower limit thereof is preferably 190 mu m or more, more preferably 220 mu m or more, and still more preferably 260 mu m or more. On the other hand, the upper limit is preferably 330 탆 or less, more preferably 310 탆 or less. It is important that the hollow fiber membrane has an inner diameter of 150 mu m or more, and the lower limit thereof is preferably 155 mu m or more, more preferably 160 mu m or more. On the other hand, the upper limit is preferably 220 탆 or less, more preferably 210 탆 or less, and further preferably 200 탆 or less.

It is important that the film thickness of the hollow fiber membrane is 30 占 퐉 or more and 90 占 퐉 or less, and the lower limit thereof is preferably 40 占 퐉 or more, more preferably 50 占 퐉 or more. On the other hand, the upper limit is preferably 80 탆 or less, more preferably 70 탆 or less.

The hollow fiber membrane of the present invention has a dense layer disposed on the outer surface side or the inner surface side of the hollow fiber membrane. In the hollow fiber membrane of the present invention, the surface of the hollow fiber membrane on which the dense layer is disposed has a plurality of holes, and the average hole diameter observed on the surface of the hollow fiber membrane of the plurality of holes is 0.3 μm or more. It is extremely excellent. On the other hand, since the average pore diameter observed on the surface of the hollow fiber membrane of the hole is 0.9 m or less, the strength of the hollow fiber membrane can be improved, and the ability to remove bacteria such as bacteria and fine particles can be improved. From the above viewpoint, the lower limit of the average pore diameter of the plurality of holes is preferably 0.35 占 퐉 or more, more preferably 0.40 占 퐉 or more. On the other hand, the upper limit of the average hole diameter of the plurality of holes is preferably 0.85 탆 or less, more preferably 0.80 탆 or less. Here, the dense layer is a scanning electron microscope (SEM) to do a hole area when observing the cross-section perpendicular to the longitudinal direction of the hollow fiber membrane is not verified by the presence of holes exceeding 0.28㎛ ^2, i.e. the hole area 0.28㎛ ² ≪ / RTI > or less. In the hollow fiber membrane of the present invention, it is preferable that no macroboid or finger void is formed on the end face of the membrane.

In the hollow fiber membrane of the present invention, the strength (DT / WT) of the hollow fiber membrane (DT) and the hollow fiber membrane (DT) is 0.24 or more, Not only resistance to high water pressure but also excellent workability and handling properties required for modularization can be obtained. The thickness of the dense layer can be measured by the method described in the examples.

It is also preferable that the dense layer of the hollow fiber membrane is disposed on the surface of the hollow fiber membrane to which the water to be treated is in contact. For example, when the water to be treated is permeated from the outer surface side to the inner surface side of the hollow fiber membrane, it is preferable to dispose the dense layer on the outer surface side of the hollow fiber membrane. This is because the detergent contained in the for-treatment water can be prevented from entering the inside of the hollow fiber membrane, so that deterioration of the filtration resistance due to the occlusion of the hole can be suppressed and deterioration of permeability of the membrane can be suppressed.

Further, the hollow fiber membrane of the present invention has a plurality of holes on the surface of the hollow fiber membrane on which the dense layer is disposed, and the opening ratio of the hollow fiber membrane is preferably 15% or more and 45% or less. When the open area ratio at the surface of the dense layer side of the hollow fiber membrane is 15% or more, it is preferable that the water permeability is excellent. On the other hand, if the open area ratio at the surface of the dense layer side of the hollow fiber membrane is 45% or less, the strength and the removal performance can be sufficiently maintained. From the above viewpoint, the lower limit of the open area ratio is more preferably 18% or more, and still more preferably 21% or more. The upper limit of the opening ratio is more preferably 42% or less, and still more preferably 39% or less. As a means for setting the opening ratio in the surface of the hollow fiber membrane at the side of the dense layer side within the above-mentioned range, it is possible to control the phase separation speed of the polymer by adjusting the dry part atmosphere in the production method of the hollow fiber membrane or to adjust the content of the hydrophilic polymer ≪ / RTI >

The hollow fiber membrane of the present invention preferably contains a hydrophilic polymer. The reason for this is that hydrophilicity is imparted to the surface of the membrane to improve the permeability and to prevent the contaminants from adhering to the membrane. On the other hand, if the content of the hydrophilic polymer is large, the hydrophilic polymer itself has opposite permeability to maintain water, and the permeability decreases. Therefore, the upper limit of the content of the hydrophilic polymer is preferably 20 parts by mass or less, more preferably 15 parts by mass or less, based on the total mass of the hollow fiber membrane. On the other hand, the lower limit thereof is preferably 3 parts by mass or more, more preferably 5 parts by mass or more. Further, even when the surface of the membrane of the hollow fiber membrane contains a large amount of cross-linked hydrophilic polymer, the decrease in permeability tends to be confirmed. Therefore, the ratio of the hydrophilic polymer to the hydrophobic polymer (hydrophilic polymer / hydrophobic polymer) on the surface of the hollow fiber membrane in which the dense layer is present is preferably 0.80 or less, more preferably 0.70 or less. From the above viewpoint, the ratio of the hydrophilic polymer to the hydrophobic polymer (hydrophilic polymer / hydrophobic polymer) on the surface opposite to the surface of the hollow fiber membrane in which the dense layer is present is preferably 0.80 or less, more preferably 0.70 or less.

Here, the hydrophilic polymer refers to a water-soluble polymer compound or a polymer compound that interacts with water molecules by electrostatic interaction or hydrogen bonding even when water-insoluble. Specific examples thereof include polyalkylene oxides such as polyethylene oxide and polypropylene oxide, polyvinyl alcohol, polyvinyl pyrrolidone (hereinafter may be referred to as PVP), polyvinyl acetate, polydimethylmethoxyacrylate, polydimethyl acrylate Amide, a copolymer of vinylpyrrolidone and acrylic acid, a nonionic hydrophilic polymer such as a copolymer of vinyl acetate and vinyl pyrrolidone, an anionic hydrophilic polymer such as polyacrylic acid, polyvinyl sulfuric acid and carboxymethyl cellulose, The cationic hydrophilic polymer such as polylysine, chitosan, and poly [methacrylic acid {2 (dimethylamino) ethyl}] is reacted with polymethacryloyloxyethylphosphoryl choline, polymethacryloyloxyethyl dimethyl ammonia propionate Of an amphoteric ionic hydrophilic polymer. The hydrophilic polymer contained in the hollow fiber membrane may be two or more kinds. In particular, a nonionic hydrophilic polymer and an amphoteric ionic hydrophilic polymer are suitably used from the viewpoint of inhibiting adhesion of the detergent.

As the material (component) constituting the substrate of the hollow fiber membrane, a hydrophobic polymer is preferable, and examples of the hydrophobic polymer include polysulfone (hereinafter sometimes referred to as PSF), polysulfone polymer such as polyether sulfone and polyallylate, A cellulose resin such as cellulose triacetate and cellulose diacetate, polymethyl methacrylate, polyacrylonitrile, polyamide and the like are suitably used. Of these, the strength of the hollow fiber membrane, From the viewpoint of water permeability, a polysulfone-based polymer is suitably used. It is particularly preferable to add PVP to the spinning solution consisting of a polysulfone-based polymer from the viewpoint of easy control of the film structure of the present invention.

The composition ratio of the hollow fiber membrane is preferably in a mass ratio (%), and the polysulfone polymer is preferably 5 to 20% of the total constituents of the hollow fiber membrane.

Further, the hollow fiber membrane preferably contains polyvinylpyrrolidone in addition to the polysulfone-based polymer. Although polyvinylpyrrolidone having various molecular weights can be used, it is preferable to use K90 (trade name, manufactured by ISP, weight average molecular weight: 1.3 million), K60 (trade name, manufactured by Tokyo Chemical Industry Co., 1600), K30 (trade name, manufactured by BASF, weight average molecular weight: 40,000) and K17 (trade name, manufactured by ISP, weight average molecular weight: 10,000). These may be mixed or polymerized in a molecular weight region other than the above.

Further, in the manufacturing process of the hollow fiber membrane, the components of the hollow fiber membrane such as polysulfone-based polymer and PVP are dissolved in a solvent to prepare a spinning solution. Here, as the solvent, a high boiling point polar solvent such as dimethylacetamide (hereinafter abbreviated as DMAc) or N-methylpyrrolidone is preferable, but any other combination can be used as long as it can dissolve uniformly.

The permeability of the hollow fiber membrane of the present invention is preferably 30 ml / Pa / hr / m 2 or more, more preferably 35 ml / Pa / hr / m 2 or more, and further preferably 40 ml / Pa / hr / . The upper limit of the permeability of the hollow fiber membrane is not particularly limited, but the permeability of the hollow fiber membrane is preferably 120 ml / Pa / hr / m 2 or less in that the permeability is too high to lower the fractionation performance More preferably 110 ml / Pa / hr / m 2 or less, and further preferably 100 ml / Pa / hr / m 2 or less.

As for the fractionation performance of the hollow fiber membrane, the removal rate of the latex bead particles having a particle diameter of 0.2 m is preferably 80% or more, more preferably 90% or more.

The hollow fiber membrane of the present invention is characterized in that the composition of the hollow fiber membrane and the composition of the injection liquid, the discharge linear velocity and the injection liquid discharge linear velocity at the time of discharging the spinning liquid from the cage, the dew point and temperature of the cold air in the dry part after discharge, The draft ratio of the time, the coagulating bath temperature, the washing condition, and the like.

Next, a method for producing the hollow fiber membrane of the present invention will be described. The hollow fiber membrane of the present invention is not particularly limited, but a spinning stock solution containing a polymer to be a material of a hollow fiber membrane may be discharged from an annular slit on the outer side, from a central pipe on the inner side by using an orifice type double- And then the hollow fiber membrane is coagulated in the coagulating solution and hot water is further added thereto to form an asymmetric hollow fiber membrane.

The spinning draft rate when producing the hollow fiber membrane of the present invention is preferably 2 or more and 6 or less. Here, the radiation draft rate is a ratio of the discharge linear velocity of the film-forming composition from the outer peripheral slit portion of the double reflexive detergent to the winding velocity of the hollow fiber membrane, and represents the value obtained by dividing the winding velocity by the discharge linear velocity of the film-forming composition. The discharge linear velocity is a linear velocity when the film-forming composition is discharged from the outer circumferential slit of the double ring detent, and is a value obtained by dividing the discharge flow rate by the outer cross-sectional area.

By setting the radiation draft rate to 2 or more, the water permeability of the hollow fiber membrane is improved. On the other hand, when the radiation draft rate is 6 or less, the radiation stability improves and the frequency of yarn breakage can be reduced. Particularly, when the yarn diameter (outer diameter) of the hollow fiber membrane is small and the radiation draft rate is high, the outer surface of the hollow fiber membrane is affected by the radiation draft, the smoothness of the outer surface is lost, So that the thickness of the dense layer tends to be thinned. If the thickness of the dense layer is reduced, the fractionation performance of the hollow fiber membrane is deteriorated, and the resistance to high water pressure (hereinafter also referred to as pressure resistance) of the hollow fiber membrane may decrease, possibly leading to yarn breakage.

When a double-ring spinneret such as an orifice-type double-loop spinneret is used for spinning the hollow fiber membrane, the spinning spinner preferably has a viscosity of 2 Pa · s or more and 11 Pa · s or less. When the viscosity of the spinning stock solution is set to 2 Pa s or more, the preparedness of the hollow fiber membrane is improved. On the other hand, by setting the viscosity of the spinning stock solution to 11 Pa s or less, the pressure in the double-ring spinning can be suppressed, and the stable discharge state of the spinning stock solution can be maintained. In view of controlling the thickness of the dense layer, if the viscosity of the spinning stock solution is too low, the viscosity of the spinning stock solution is preferably 2 Pa s or more even in that the phase separation rate of the polymer is increased and the thickness of the dense layer becomes too thin.

On the other hand, the liquid to be injected into the central pipe of the double ring detent can be appropriately selected to be solidified or non-solidified in conformity with the shape of the desired hollow fiber membrane. There is a coagulation value as an index of coagulability of the injected liquid. This solidification value means the added mass of the liquid to be injected at the time when the solution was opaque by adding the injection liquid in small amounts to 50 g of the 1 mass% solution of the main polymer constituting the membrane. The smaller the value of the coagulation value is, the higher the coagulation property of the injection liquid is. If the coagulation value is 40 g or more (more than 80% of the original liquid amount) from the past experience rule, the particle structure of the cohesive polymer is not visible on the surface of the film on which the dense layer is formed, and therefore,

When a coagulating liquid is used for such injection liquid, solidification starts from the inner surface, so that a dense layer is formed on the inner surface side of the hollow fiber membrane. On the other hand, when a non-immiscible liquid is used, solidification starts from the outer surface by the coagulating bath installed on the downstream side, so that a dense layer is formed on the outer surface side of the hollow fiber membrane. Therefore, in the case of a water purifier used as a flow for filtering from the outer surface side to the inner surface side of the hollow fiber membrane, a non-extensible liquid is particularly preferably used.

In particular, the absolute value of the discharge linear velocity of the spinning stock solution and the injection liquid and the relative value of both have a great influence on the structure formation of the dense layer. It is presumed that the orientation of the polymer is determined by the discharge linear velocity.

If the absolute value of the discharge linear velocity of the spinning stock solution is excessively high, the water permeability of the hollow fiber membrane obtained becomes low. If the absolute value of the discharge linear velocity is too low, the smoothness of the outer surface of the hollow fiber membrane obtained is lost, The thickness tends to be reduced. The separation performance of the hollow fiber membrane is deteriorated, the resistance to high water pressure of the hollow fiber membrane is lowered, and yarn breakage may occur depending on the case. Therefore, the absolute value of the discharge linear velocity of the spinning stock solution is preferably 0.05 m / s or more, more preferably 0.1 m / s or more. On the other hand, it is preferably 0.3 m / s or less, and more preferably 0.25 m / s or less.

If the absolute value of the discharge linear velocity of the injection liquid is excessively high, the pressure loss of the central pipe of the double reflux condenser becomes high, and the outer diameter deviation of the hollow fiber membrane to be obtained becomes large. If the absolute value of the discharge linear velocity is too low, a plate structure is formed on the inner surface of the obtained hollow fiber membrane to lower the resistance to high water pressure of the hollow fiber membrane, which sometimes causes yarn breakage. Therefore, the absolute value of the discharge linear velocity of the injection liquid is preferably 0.05 m / s or more, more preferably 0.1 m / s or more. On the other hand, it is preferably 0.5 m / s or less, and more preferably 0.3 m / s or less.

If the relative value of the spinning rate of the spinning liquid and the injection liquid is too high, a plate structure is formed on the outer surface of the hollow fiber membrane to be obtained, and the thickness of the dense layer tends to be thin. When the thickness of the dense layer is reduced, the fractionation performance of the hollow fiber membrane is deteriorated, the resistance to high water pressure of the hollow fiber membrane is lowered, and in some cases, yarn breakage is undesirable. In addition, if the relative value of the discharge linear velocity of the spinning stock solution and the injection liquid is too small, the water permeability of the resultant hollow fiber membrane is lowered, which is not preferable. Here, the relative value of the discharge linear velocity of the spinning stock solution and the injection liquid is a value obtained by dividing the discharge linear velocity of the injection liquid by the discharge linear velocity of the spinning solution. Therefore, the relative value of the discharge linear velocity of the spinning stock solution and the injection liquid is preferably 0.5 or more, and more preferably 0.6 or more. On the other hand, it is preferably 2.0 or less, more preferably 1.5 or less.

When the thread diameter of the hollow fiber membrane is made narrow, the deviation of the outer diameter easily becomes large, which disrupts the hollow fiber membrane structure and causes a problem in quality such as pressure resistance, water permeability and fractionation performance. Therefore, the outer diameter deviation of the hollow fiber membrane is preferably 15% or less, more preferably 10% or less. The outer diameter deviation was evaluated by the method described in the examples. As means for setting the deviation of the outer diameter of the hollow fiber membrane within the above range, there is a method of controlling the dimension of the annular slit of the double ring detent or the pressure loss of the center pipe of the double ring detent.

In the spinning process of the hollow fiber membrane, when phase separation of the hollow fiber membrane is caused by heat, it is quenched in a coagulating bath and solidified after cooling in a dry part. When phase separation of the hollow fiber membrane is caused by a poor solvent in the spinning process of the hollow fiber membrane, the spinning solution is contacted with a coagulating solution containing a poor solvent, and is discharged and solidified in a coagulating bath comprising a poor solvent. In addition, in the method of inducing phase separation of the hollow fiber membrane with the poor solvent, the supply amount of the poor solvent in the membrane thickness direction of the hollow fiber membrane is changed because the poor solvent is supplied to the inside of the hollow fiber membrane by diffusion. Therefore, the structure has such a structure that the hole diameter of the cross section in the film thickness direction of the hollow fiber membrane becomes larger from one surface of the hollow fiber membrane toward the other surface. Therefore, it is preferable that the coagulating solution containing the poor solvent and the spinning stock solution come into contact immediately after discharge. By adjusting the concentration of the coagulating liquid as a mixture of a poor solvent and a good solvent, the coagulation property is changed, and the diameter of the hole on the side in contact with the coagulating liquid and the thickness of the dense layer can be controlled.

On the side where the coagulating solution and the spinning stock solution come into contact with each other, phase separation is induced and the progress of solidification is fast, resulting in a dense structure having a small hole diameter. Further, the hole diameter continuously increases toward the opposite direction of the side where the coagulating solution and the spinning stock solution come in contact with each other. Here, if the passage time of the dry part is long enough, the diameter of the hole on the side not in contact with the coagulating solution grows large. Therefore, the passage time of the dry part is shortened, so that it is immersed in the coagulation bath at a high speed, so that solidification at the side not in contact with the coagulating solution proceeds by contact with the poor solvent of the coagulation bath, and a dense structure having a small pore diameter can be formed.

The passage time of the dry part is preferably not less than 0.02 seconds, more preferably not less than 0.14 seconds, depending on conditions of influencing the progress of phase separation such as the composition and temperature of the spinning stock solution. On the other hand, it is preferably 0.40 seconds or less, more preferably 0.35 seconds or less.

The concentration of the poor solvent in the coagulating bath is preferably not less than 30 parts by mass, more preferably not less than 50 parts by mass, and even more preferably not less than 80 parts by mass based on the whole coagulating liquid.

The temperature of the coagulating bath is preferably 50 占 폚 or higher, more preferably 60 占 폚 or higher because the temperature of the coagulating bath is high and the solvent exchange in the coagulating bath is likely to occur and the amount of solvent remaining in the hollow fiber membrane can be reduced. More preferably 70 DEG C or higher.

When the temperature of the coagulating bath is high, condensation may be formed on the holding surface, thereby causing yarn breakage. Therefore, the discharge temperature of the spinning stock solution is preferably 25 DEG C or higher in order to prevent condensation on the surface to be impregnated. When the discharge temperature of the spinning stock solution is excessively high, the discharge temperature of the spinning stock solution is preferably 70 ° C or less, more preferably 55 ° C or less, because radioactivity tends to become unstable.

The coagulating bath concentration changes with the supply of the solvent from the spinning stock solution or coagulating solution with the passage of time. Therefore, it is preferable to increase the liquid amount of the coagulating bath to suppress the change in concentration, or to adjust the concentration from time to time by monitoring the concentration.

In the dry part, it is preferable to set a running zone in which the temperature and humidity are more actively humidified, in view of controlling the opening of the hollow fiber membrane, and to reduce unevenness in the performance of the obtained hollow fiber membrane.

Further, in the dry part, there is no particular limitation, but in order to more actively humidify the dry part atmosphere, it is preferable to provide a cold air tube on both sides of the spinning stock solution discharged from the double-ring spinning nozzle or around the spinning solution discharged from the double- And an annular cool air circulation tube is enclosed. In the case of installing the cold air vents on both sides of the spinning liquid discharged from the two-way air intakes, a method of supplying cold air from one side of the cold air vents and discharging the cold air from the other side and a method of supplying cold air from both sides, It is preferable in that it can more actively humidify. Also, in the case of surrounding the periphery of the spinning liquid discharged from the double-ring spinning nozzle with the annular cold air cooling tube, the dry part is less likely to be influenced by the outside air, and the unevenness in performance of the obtained hollow fiber membrane can be reduced.

In the dry part, as the dew point of the cold air and the wind speed increase, the supply amount of the water as the poor solvent increases, so that it is effective when the hole diameter of the outer surface is increased to increase the open rate. The dew point of the dry part is preferably 18 DEG C or more, more preferably 21 DEG C or more. The wind speed of the cold air in the dry part is preferably 0.1 m / s or more, more preferably 0.5 m / s or more. On the other hand, since the wind speed of the cool air is lowered, the surface of the spinning stock solution under discharge can be suppressed from being disturbed or shaking under discharge, so that the wind speed of the dry part is preferably 10 m / s or less and more preferably 5 m / s or less.

The length of the dry part is preferably 10 to 200 mm in order to make the hole diameter of the surface of the hollow fiber membrane appropriate, while preventing the thread shake during film formation.

A poor solvent is a solvent which does not dissolve a polymer mainly constituting a hollow fiber membrane structure at a film forming temperature.

The poor solvent may be appropriately selected depending on the kind of the polymer, but water is suitably used. Both the solvents may be appropriately selected depending on the kind of the polymer. When the polymer to be the structure of the hollow fiber membrane is a polysulfone-based polymer, N, N-dimethylacetamide is suitably used.

According to the above production method, although the hollow fiber membrane is obtained in the wet state, since the permeability of the hollow fiber membrane is unstable, cross-linking reaction of moisture drying and hydrophilic polymer (PVP, etc.) is required. As described above, when a hydrophilic polymer (PVP or the like) is contained, hydrophilicity can be imparted to the hollow fiber membrane, and improvement of the water permeability and adhesion of the contaminants to the membrane can be suppressed. However, the hydrophilic polymer remaining in the film may be slightly eluted. This is undesirable for medical applications and food industry applications. As a cross-linking reaction for insolubilization,? -Ray irradiation is effective for a vinyl-based hydrophilic polymer. In addition, when the hydrophilic polymer is polyvinylpyrrolidone, crosslinking can be carried out by heating. The drying temperature is preferably 100 DEG C or higher in terms of evaporating water. The heat treatment temperature for crosslinking is preferably about 5 hours at 170 ° C, about 2.5 hours at 180 ° C, and about 1.5 hours at 190 ° C. The higher the temperature, the shorter the processing time. When the temperature is 150 DEG C or less, the treatment time is too long, which is not practical.

When drying is carried out in the state that a large amount of the hydrophilic polymer is contained in the hollow fiber membrane when the hollow fiber membrane is dried, the hydrophilic polymer is distributed on the surface of the hollow fiber membrane, and the permeation performance of the hollow fiber membrane or the filtration rate The hollow fiber membrane obtained by the pretreatment is preferably washed with hot water. The temperature of the hot water is preferably 60 DEG C or higher, more preferably 70 DEG C or higher, and even more preferably 80 DEG C or higher. Further, it is preferably 99 DEG C or lower. The mass of the hydrophilic polymer after the hot water washing is preferably 3 parts by mass or more and 20 parts by mass or less, more preferably 5 parts by mass or more and 10 parts by mass or less, based on the mass of the whole membrane.

The hollow fiber membrane of the present invention can be suitably used for a water purifier cartridge as described above. Further, as a method for manufacturing a cartridge for a water purifier on which a hollow fiber membrane is mounted, a conventionally used method can be adopted.

Example

Hereinafter, the present invention will be described in detail by way of examples, but the present invention is not limited thereto.

(Analysis method and evaluation method)

(1) Viscosity measurement:

A B type viscometer shown in JIS K7117 (1999) was used, and an average value of n = 3 was referred to as a measured value.

(2) Measurement of permeability performance

The hollow fiber membranes were inserted into a case provided with holes for reflux liquid at both ends, the both ends were potted with an epoxy resin adhesive "Quick Mender" (registered trademark) manufactured by Konishi Co., Ltd., and a hollow fiber membrane and potting agent A compact module having an effective length of 12 cm was produced. The water permeability was measured by measuring the amount of water passing through the hollow fiber membrane outside the hollow fiber membrane within a certain period of time, applying the water pressure inside the hollow fiber membrane at 37 ° C in a constant temperature water bath, did. That is, the permeability (UFRS) of the hollow fiber membrane was calculated by the following formula.

UFRS (mL / hr / Pa / m 2) = Qw / T / P / A

Qw: (pass) filtrate (mL)

T: Leakage time (hr)

P: pressure (Pa)

A: Membrane area of hollow fiber membrane (m 2)

(3) Measurement of aperture ratio of the surface of the hollow fiber membrane and the hole diameter of the hollow fiber membrane

5000-fold image of the outer surface of the hollow fiber membrane was taken with an SEM (S-5500, manufactured by Hitachi High-Technologies Corporation) and introduced into a computer. Then, analysis processing was performed with image processing software. An SEM image was binarized to obtain an image in which the hole portion was inverted to black and the structural polymer portion was inverted to white. The total area S of the holes was read out and the open area ratio (%) per one image was calculated by the following formula.

Open area ratio (%) = S (占 퐉 ² ) / Image size (占 퐉 ² ) 占 100

Also, regarding the average pore diameter, the analysis processing was similarly performed by the image processing software. The SEM image was binarized to obtain an image in which the hole was black and the structural polymer portion was white. The total area S (占 퐉 ² ) of holes and the number of black holes (hereinafter, total number of holes) were read and the average hole area (占 퐉 ² ) was calculated by the following equation. Further, the average pore diameter (占 퐉) was calculated from the average pore area (占 퐉 ² ). This calculation was performed assuming that the pore shape was a true circle.

Average hole area (占 퐉 ² ) = S (占 퐉 ² ) / Total number of holes

Average pore diameter (占 퐉) = 2 占 (average pore area /?)

This operation was performed on five different hollow fiber membranes, and the arithmetic average was obtained.

(4) Measurement of the thickness (DT) of the dense layer

The SEM (S-5500, manufactured by Hitachi High-Technologies Corporation) was used to measure the cross-section perpendicular to the longitudinal direction of the hollow fiber membrane which was used as the observation sample of the folded section at a rapid rate, and the hollow fiber membrane was immersed in water for 5 minutes, An image was introduced into the computer so that the front side on the side where the structure portion was denser was located on the left side of the image and the front side on the side where the structure portion was rough was located on the right side of the image. In the following description, the hollow fiber membrane is described in which the structure portion is dense on the outer surface side for convenience and the structure portion is rough on the inner surface side. In the case of a hollow fiber in which the structure portion is dense on the inner surface side and the structure portion is rough on the outer surface side, the outer surface described below may be replaced with the inner surface and the inner surface with the outer surface.

The size of the introduced image was 640 pixels x 480 pixels. When the hollow portion of the hollow fiber membrane on the cross section was obscured by SEM observation, the sample was again made. The occlusion of the hollow portion may occur when the hollow fiber membrane is deformed in the direction of stress during the cutting process. Further, when the dense layer was not stable in the observation field of the measurement magnification, two or more SEM images were synthesized so that the dense layer was stabilized. An image in which the hole portion was black and the structure portion was white was obtained by binarization. When the structure portion and the other portions were not divided by the difference in contrast in the image, the images were divided into portions having the same contrast, and subjected to binarization processing, respectively, Alternatively, image analysis may be performed by filling the portion other than the structural portion with black. In the case where the hole was observed doubly in the depth direction, it was measured in the hole at the shallow side. Further, the hole area was obtained by analyzing the area of a single portion of the hole, which is displayed in black by the binarization of the image, by image processing software.

The number of pixels of the scale bar representing the known length in the image was measured and the length (占 퐉) per one pixel was calculated. The size of the introduced image was 42.38 mu m in width x 31.79 mu m in length.

Holes having a hole area of 0.28 占 퐉 ^{2 or more} were painted with a fluorescent color without a gap and the hole-free layer having a hole area exceeding 0.28 占 퐉 ² was formed as a dense layer, and the inner surface direction from the outer surface of the hollow fiber membrane To measure the thickness of the dense layer. However, there are cases where holes having a hole area exceeding 0.28 탆 ² are identified near the surface of the dense layer by the influence of the film formation method of the hollow fiber membrane. In addition, this dense layer surface a plurality of holes in the vicinity of the hole area 0.28㎛ ² or less or the like even by the focus of the image that does not fit effect is recognized as one hole as the hole to the hole area exceeds 0.28㎛ ² tightly by fluorescent It may be painted. If this is the case, the accurate dense layer thickness can not be measured. Therefore, when holes having a hole area of 0.28 탆 ² or more exist at a position within 10% of the film thickness (6 탆 when the film thickness is 60 탆) from the outer surface of the hollow fiber membrane, they are ignored as noise .

Specifically, the thickness of the dense layer was measured as follows. First, a straight line perpendicular to the outer surface in the thickness direction of the hollow fiber membrane, that is, from the outer surface to the inner surface of the hollow fiber membrane was drawn. And holes having a hole area nearest to the outer surface of 0.28 mu m < ² > from the holes existing on this straight line were searched. The intersection of this hole and the side near the outer surface of the intersection of the straight line was selected and the distance between the intersection and the outer surface was taken as the thickness of the dense layer.

For the introduced image (42.38 mu m in length x 31.79 mu m in length), the image was divided into three in the longitudinal direction to obtain three images of 42.38 mu m in width x 10.6 mu m in length. Subsequently, the thickness of the dense layer at the middle point of the vertical direction of each field of view was measured as described above.

The thickness of the dense layer was obtained from the images of each of the three views of division, and similar measurements were made from the 20 introduced images to obtain measurement data of the thicknesses of 60 dense layers in total. The average value of 60 measurement data was calculated and defined as the thickness (DT) of the dense layer having only a hole having a hole area of 0.28 탆 ² or less.

(5) Hydrophilic polymer / hydrophobic polymer on the surface of the hollow fiber membrane

The measurement sample of the hollow fiber membrane containing the hydrophilic polymer and the hydrophobic polymer is set in the sample holder, the sample holder is set on the plate, the knob is turned, and the surface (outer surface or inner surface) . Subsequently, the surface to be measured of the hollow fiber membrane was analyzed using an infrared ATR measuring apparatus (manufactured by JASCO Corporation, infrared spectrophotometer: FT / IR-6000, infrared microscope: IRT-3000), and the hydrophilic polymer And hydrophobic polymer ratio (hydrophilic polymer / hydrophobic polymer). Hereinafter, the case of using PVP as the hydrophilic polymer and PSF as the hydrophobic polymer will be exemplified and the measurement method will be described in detail.

The PSF of 1580㎝ ^-1 vicinity from the infrared absorption spectrum obtained by an analysis by the infrared ATR measuring the benzene ring C = C of the absorption derived from the peak area of the (Acc) and the amide bond in the vicinity of the PVP-derived 1650㎝ ^-1 The area Aco of the absorption peak was calculated and the ratio Aco / Acc of the peak area was obtained. The peak area ratio was determined for 30 hollow fiber membranes in the same manner, and the average value of the measurement data of the system 30 was calculated to obtain the PVP / PSF ratio (PVP / PSF) of the surface to be measured for the hollow fiber membrane.

(6) Measurement of 0.2 mu m particle removal rate

A small module was produced in the same manner as in (2) above. A polystyrene latex bead suspension (manufactured by Invitrogen, Sulfate latex) having a concentration of 200 ppm was supplied from the outside of the hollow fiber membrane, and the concentration of the suspension permeated inward through the hollow fiber membrane was measured. Using the feed side concentration of 200 ppm and the permeate side concentration value, the rejection rate was obtained from the following formula. The latex beads having a particle size of 0.2 mu m (actual value 0.203 mu m) were used.

Reject rate = 1-Cp / Cf

Cp: permeation-side concentration

Cf: Supply side concentration

The relationship between the absorbance at 260 nm and the latex bead concentration was measured in advance, and the concentration was determined by measuring the absorbance of the suspension on the permeation side. Absorbance was measured using a spectrophotometer (U-5100, Hitachi, Ltd.).

(7) Measurement of inner diameter and film thickness of hollow fiber membrane

The hollow fiber membrane was cut in a thickness direction in a thickness direction and set on a micro-wipe (VH-Z100 manufactured by KEYENCE CORPORATION). When the hollow fiber cross-section was broken by cutting, the cutting was repeated until the fiber end was about to be rounded. The cross-section of the hollow fiber membrane was observed with a 1000-fold lens, and the film thickness width of the hollow fiber membrane was specified on the monitor screen on which the cross section was projected to read the numerical value displayed on the monitor screen. Further, the hollow fiber membrane inner diameter is displayed on the monitor screen by designating the width of the hollow portion. The same measurement was carried out for 30 hollow fiber membranes and the average value of the measurement data of the system 30 was calculated to be the inner diameter (ID) and the film thickness (WT) of the hollow fiber membrane.

(8) The ratio (DT / WT) of the thickness (DT) of the dense layer to the film thickness (WT)

The ratio of the thickness DT of the dense layer to the thickness WT of the hollow fiber membrane from the thickness DT of the dense layer calculated in (4) and the film thickness WT of the hollow fiber membrane calculated in (7) DT / WT).

(9) Measurement of outer diameter and outer diameter deviation of hollow fiber membrane

The hollow fiber membrane cut into 30 cm in the longitudinal direction was set on an outer diameter measuring instrument (LS-5500, manufactured by KEYENCE CORPORATION, controller section: LS-5040, sensor head section: LS-5040) and the outer diameters of the hollow fiber membranes Respectively.

The same measurement was performed on 20 hollow fiber membranes, and the average value of the measurement data of the system 40 was calculated to obtain the OD (OD) of the hollow fiber membrane. Further, a value (MAX) having the largest outer diameter and a value (MIN) having the smallest outer diameter were selected from the measurement data of the system 40, and the outer diameter deviation (ROD) was calculated by the following formula.

ROD (%) = (MAX-MIN) / OD x 100

(10) Withstand pressure performance

The hollow fiber membrane was inserted into an acrylic pipe, the both ends were potted with an epoxy resin adhesive "Quick Mender" (registered trademark) manufactured by Konishi Co., Ltd., and the hollow fiber membrane projected from both ends of the case and the potting agent were cut to manufacture a small module did.

Within the tank, the small modules were connected using joints to the air bomb, pressure regulator, pressure gauge, dial gauge, and circuit to which the opening and closing cork was connected.

The pressure gauge was called the pressure resistance performance when the dial gauge was opened slowly and cracks were formed in the hollow fiber membrane in the small module and the pressure suddenly dropped. If the air leaked on the way, it was done again from the beginning.

(11) Hollow fiber membrane filtration flow rate

A tube was connected so that raw water could be supplied to the non-opening side of the hollow fiber membrane module, water at 20 ° C was supplied at 0.1 MPa, the amount of water per unit time flowing out through the hollow fiber membrane was measured, (L / min) was calculated.

(12) Water purifier Cartridge filtration ability

Activated carbon was placed on the upstream side of the fabricated hollow fiber membrane module and made into a cartridge, followed by the method shown in JIS S 3201: 2004 (domestic water purifier test method). The initial flow rate was set at 2.0 L / min.

(Example 1)

, 15 parts by mass of a hydrophobic polymer (PSF (Solvay Udel Polysulfone (registered trademark) P-3500) and 7 parts by mass of a hydrophilic polymer (PVP (ISP K90)) and 75 parts by mass of N, N-dimethylacetamide (DMAc) And 3.0 parts by mass of water were dissolved and stirred to prepare a spinning solution. The viscosity of this spinning solution at 37 캜 was 5.0 Pa s. This spinning stock solution was discharged from the annular slit of the double-ring spinning nozzle. 55 parts by mass of DMAc, 30 parts by mass of polyvinylpyrrolidone (BASF K30, weight average molecular weight 40,000) and 15 parts by mass of glycerin were injected from the central pipe as the injection liquid. The custody was kept at 37 ℃. The ratio of the discharge linear velocity of the injection liquid and the spinning fluid to that of the spinning fluid was 0.8.

A cold air tube was installed in the dry part, and the cold air was passed from both sides of the spinning stock solution to pass the predetermined dry length. The dry part dew point during spinning was as shown in Table 1. The spinning solution passed through the dry part was immersed in a coagulating bath at 80 DEG C containing a mixed solution composed of 90 parts of water and 10 parts of DMAc, and was coagulated. The resultant was further subjected to hot water washing in a hot bath at 80 DEG C and then wound on a reel, ≪ / RTI > The wound hollow fiber membrane had an outer diameter of 300 mu m, an inner diameter of 180 mu m, and a film thickness of 60 mu m. The resultant hollow fiber membrane was cut into 30 cm in the longitudinal direction and washed with hot water at 90 캜 for 3 hours. The hollow fiber membrane was dried in a dry heat dryer and heat-treated at 160 ° C or higher to obtain a dry hollow fiber membrane.

1994) of the hollow fiber membrane in a dry state was folded in U-shape and inserted into a tubular case (inner diameter: 26 mm, length: 45 mm), and the opening was fixed with a polyurethane resin to obtain a hollow fiber membrane module.

Table 1 and Table 2 show the composition and various performances of the obtained hollow fiber membranes, the filtration flow rate of the hollow fiber membrane module, and the filtration ability of the water purifier cartridge.

(Example 2)

A hollow fiber membrane in a wet state was obtained in the same manner as in Example 1. The obtained hollow fiber membrane was cut to a length of 30 cm, the hollow fiber membrane was dried in a dry heat dryer, and heat-treated at 160 ° C or higher to obtain a dry hollow fiber membrane.

1994 was folded in a U-shape and inserted into a tubular case (inner diameter: 26 mm, length: 45 mm), and the opening was fixed with a polyurethane resin to obtain a hollow fiber membrane module.

Table 1 and Table 2 show the composition and various performances of the obtained hollow fiber membranes, the filtration flow rate of the hollow fiber membrane module, and the filtration ability of the water purifier cartridge.

(Example 3)

A hollow fiber membrane in a wet state was obtained in the same manner as in Example 1. The resultant hollow fiber membrane was cut into 30 cm in the longitudinal direction and washed with hot water at 90 캜 for 3 hours. The hydrophilic polymer in the hollow fiber membrane was crosslinked by gamma irradiation (25 kGy).

Fourteen hollow fiber membranes after irradiation with gamma rays were folded into a U-shape, inserted into a tubular case (inner diameter: 26 mm, length: 45 mm), and the openings were fixed with polyurethane resin to form a hollow fiber membrane module.

Table 1 and Table 2 show the composition and various performances of the obtained hollow fiber membranes, the filtration flow rate of the hollow fiber membrane module, and the filtration ability of the water purifier cartridge.

(Comparative Example 1)

The same procedure as in Example 1 was carried out except that the spinning liquid was discharged from the annular slit of the double-ring spinning nozzle at a discharge linear velocity of 0.003 m / s and the injection liquid was discharged from the injection liquid pipe at a discharge linear velocity of 0.04 m / A hollow fiber membrane was obtained. The actual diameter of the hollow fiber membrane was 300 mu m in outer diameter, 180 mu m in inner diameter, and 60 mu m in film thickness. The ratio of the discharge linear velocity of the spinning stock solution to the injection liquid velocity was the injection liquid discharge linear velocity / discharge liquid discharge linear velocity of 13.3.

1994 was folded in a U-shape and inserted into a tubular case (inner diameter: 26 mm, length: 45 mm), and the opening was fixed with a polyurethane resin to obtain a hollow fiber membrane module.

Table 1 and Table 2 show the composition and various performances of the obtained hollow fiber membranes, the filtration flow rate of the hollow fiber membrane module, and the filtration ability of the water purifier cartridge. The outer surface of the hollow fiber membrane was observed with an SEM (S-5500, manufactured by Hitachi High-Technologies Corporation), and the film structure on the outer surface was elongated in the longitudinal direction to form a plate structure. As a result, the thickness of the dense layer in the hollow fiber membrane becomes smaller and the hollow fiber membrane becomes less resistant to pressure.

(Comparative Example 2)

The hollow fiber membranes were wound on a reel in the same manner as in Example 1 except that the spinning solution had a viscosity of 1.5 Pa · s and was discharged from a ring-shaped slit of the double-ring spinning nozzle. However, Which is repeatedly generated. The evaluation results of the hollow fiber membrane are shown in Tables 1 and 2. Some of the collected hollow fiber membranes were very thin with a dense layer thickness of 27%. Because of the large ROD, the performance of the hollow fiber membrane became unstable and the quality of the hollow fiber membrane deteriorated. In addition, the quality of the hollow fiber membrane of Comparative Example 2 was poor, and the hollow fiber membrane could not be formed into a bundle and U-shaped. Therefore, it was not possible to fabricate a hollow fiber membrane module to evaluate the module filtration flow rate. In the hollow fiber membrane of Comparative Example 2, it was not possible to evaluate the filtration capacity of the hollow fiber membrane module and the filtration ability of the purifier cartridge.

(Comparative Example 3)

The same procedure as in Example 1 was carried out except that the spinning liquid was discharged at a discharge linear velocity of 0.28 m / s from the annular slit of the double-ring retort, and the injection liquid was discharged at a discharge linear velocity of 0.22 m / s from the injection liquid pipe. A hollow fiber membrane was obtained. The actual diameter of the hollow fiber membrane was 360 mu m in outer diameter, 220 mu m in inner diameter, and 70 mu m in film thickness. The ratio of the discharge linear velocity of the spinning stock solution to the injection liquid velocity was the injection liquid discharge linear velocity / the spinning liquid discharge linear velocity = 0.79.

The 1384 hollow fiber membranes in a dry state were folded into a U shape and inserted into a tubular case (inner diameter: 26 mm, length: 45 mm), and the openings were fixed with polyurethane resin to obtain a hollow fiber membrane module.

Table 1 and Table 2 show the composition and various performances of the obtained hollow fiber membranes, the filtration flow rate of the hollow fiber membrane module, and the filtration ability of the water purifier cartridge.

Although the present invention has been described in detail with reference to specific embodiments, it is apparent to those skilled in the art that various changes and modifications can be made without departing from the spirit and scope of the present invention. The present application is based on Japanese patent application (Japanese Patent Application No. 2016-056695) filed on March 22, 2016, the content of which is incorporated herein by reference.

(Industrial availability)

The present invention can be used as a hollow fiber membrane applicable to a hollow fiber membrane module or a water purifier cartridge in the water treatment field. In addition to water purifiers, they can also be used for medical applications such as plasma membranes.

Claims (5)

A hollow fiber membrane having a dense layer having only a hole having a hole area of 0.28 탆 ² or less in a state of being observed in a cross section perpendicular to the longitudinal direction of the hollow fiber membrane,
The dense layer is disposed on the outer surface side or the inner surface side of the hollow fiber membrane,
The outer diameter of the hollow fiber membrane is 350 mu m or less,
Wherein the hollow fiber membrane has an inner diameter of 150 mu m or more,
The membrane thickness of the hollow fiber membrane is 30 占 퐉 or more and 90 占 퐉 or less,
Wherein the surface of the hollow fiber membrane on which the dense layer is disposed has a plurality of holes and an average pore diameter observed on the surface of the hollow fiber membrane of the plurality of holes is not less than 0.3 mu m and not more than 0.9 mu m,
Wherein a ratio DT / WT of a thickness (DT) of the dense layer to a film thickness (WT) of the hollow fiber membrane is 0.24 or more. The method according to claim 1,
And the dense layer is disposed on the outer surface side of the hollow fiber membrane. 3. The method according to claim 1 or 2,
Wherein the density of the surface of the hollow fiber membrane on which the dense layer is disposed is 15% or more and 45% or less. 4. The method according to any one of claims 1 to 3,
A hollow fiber membrane comprising a polysulfone-based polymer and polyvinylpyrrolidone. A cartridge for a water purifier equipped with the hollow fiber membrane according to any one of claims 1 to 4.